JP4377287B2 - Multilayer sheet and package comprising the multilayer sheet - Google Patents

Description

  The present invention relates to a multilayer sheet and a package comprising the multilayer sheet.

  Various products displayed in supermarkets and convenience stores are always exposed to lighting such as fluorescent lights. For packaging of dairy products and oil-containing foods that are affected by irradiated light, particularly ultraviolet rays, a packaging material having a low light transmittance and excellent light shielding properties is used. As a technique for obtaining such a packaging material, a technique for performing aluminum foil or aluminum vapor deposition on the packaging material is known.

On the other hand, as a packaging material, a sheet made of a synthetic resin material (plastic), which is a general-purpose material, is widely used. However, this synthetic resin material is easy to mold, but it alone has insufficient light shielding properties. It was necessary to impart light shielding properties.
In addition, as another issue, in recent years, plastic products have been required to be adaptable to the environment from the development stage due to problems such as the generation of toxic gases during combustion in industrial waste made of plastic. There has been a demand for the development and use of plastic products with excellent recyclability.

  In order to impart light shielding properties and concealing properties to a sheet made of a synthetic resin material, for example, a white pigment such as titanium oxide is blended with a resin material constituting the sheet to form a white layer, or a black pigment such as carbon black. As a black layer by blending these, a technique of using these as a laminate is provided (for example, Patent Document 1 and Patent Document 2). However, since many of these sheets have a black layer exposed on the outermost surface, they are inferior in cleanliness and are not preferable for use in packaging foods.

Therefore, a sheet material that does not have a black layer on the outermost surface has been studied. For example, the central layer is a black layer, the layer laminated with the central layer is a white layer, and the outermost layer is a non-colored layer (colored). A film provided with a layer not to be applied has been proposed (for example, Patent Document 3). As another example, a paper package in which a paper layer and a synthetic resin layer such as a black layer, a white layer, a gas barrier layer, and a surface coat layer are laminated has been proposed (for example, Patent Document 4).
JP-A-6-263980 JP-A-11-91042 JP 2003-326654 A Japanese Patent Laid-Open No. 2002-2658

  However, since the film disclosed in Patent Document 3 has a configuration in which a white layer is disposed between the layers, the recycled material of the sheet cannot be applied between the layers, and a problem remains in recyclability. It was. Moreover, since the paper packaging body disclosed in Patent Document 4 includes paper material, it cannot be recycled with respect to the synthetic resin material, and it is difficult to stack the paper material and the synthetic resin material, which leads to an increase in cost. There was a problem. Furthermore, such a paper packaging body has a limit in the field which can be used, and could not be said to be a practical packaging material.

  Therefore, the object of the present invention is to provide a white cleanliness required for packaging of various articles such as foods, the content contact surface is hygienic, possesses high light shielding properties, and is self-recycled in the sheet. An object of the present invention is to provide a multilayer sheet that can be used and a package comprising the multilayer sheet.

In order to solve the above problems, the multilayer sheet of the present invention comprises a concealing layer containing a white pigment, and concealing the auxiliary layer containing a white pigment及beauty black color pigment, and the light-shielding layer containing Kokushokukao fees, A multilayer sheet provided with non-colored layers in this order, a second concealment auxiliary layer containing a white pigment and a black pigment between the light-shielding layer and the non-colored layer, and a second containing a white pigment comprising a hiding layer in this order, wherein the white pigment hiding layer has a larger content than the white pigment of the hiding auxiliary layer, the white pigment of the second shielding layer is than white pigment of the second concealment auxiliary layer large content, the white pigment light-shielding layer is the hiding auxiliary layer and smaller content than the white pigment of the second concealment auxiliary layer, the hiding layer and the second hiding layer, the content of each of the white pigment The rate is 0.97 to 8.21 g / m ² , and the concealment auxiliary layer and Said second concealing the auxiliary layer, the black content of the white pigment are each a 0.10~3.91g / m ^2, the light shielding layer, it is contained in the concealing auxiliary layer and the second hiding auxiliary layer pigment, wherein a 0.03 to 1 wt% with respect to the multilayer sheet, characterized in that the black pigment of the light shielding layer, the hidden auxiliary layer and content than the black pigment of the second concealment auxiliary layer is large And
In the multilayer sheet of the present invention, the light shielding layer has a black pigment content of 0.30 to 8.00 mass%, and the concealment auxiliary layer and the second concealment auxiliary layer are each composed of a black pigment. The content is preferably 0.01 to 0.25% by mass.

This multilayer sheet of the present invention comprises a hiding layer, a hiding auxiliary layer, a light shielding layer, and a non-colored layer in this order, and the total amount of white pigment contained in the hiding layer and hiding auxiliary layer is 0.5 g / m ² or more, and the white pigment content of the hiding layer is larger than the white pigment content of the hiding auxiliary layer.
As a result, in the multilayer sheet, the brightness of the hiding layer is greater than that of the hiding auxiliary layer, and the whiteness of the sheet (whiteness) is the highest in the hiding layer as the outer layer, so that it has a good appearance with a clean feeling. A multilayer sheet. Moreover, it becomes a multilayer sheet excellent in concealability by further providing not only the concealment layer which is a white layer but the concealment auxiliary layer whose whiteness is lower than the concealment layer.

Further, the black pigment contained in the light shielding layer and the masking auxiliary layer is 0.03 to 1% by mass with respect to the multilayer sheet, and the white pigment in the light shielding layer has a smaller content than the white pigment in the masking auxiliary layer, and the light shielding is performed. Since the black pigment of the layer has a higher content than the black pigment of the concealment auxiliary layer, the brightness of the concealment auxiliary layer in the multilayer sheet is larger than that of the light shielding layer. Therefore, the degree of black (blackness) increases stepwise toward the inside of the sheet, resulting in a multilayer sheet having a high light shielding property against external light. The hiding auxiliary layer is laminated between the hiding layer and the light shielding layer, so that the hiding property of the sheet can be supplementarily improved and the light shielding property of the sheet can be improved.
In the present invention, the “sheet” includes not only the sheet itself but also what is called a thin “film”.

  In the multilayer sheet of the present invention, the concealment auxiliary layer exhibiting white to gray and the light shielding layer exhibiting gray to black are not shown on the outer surface of the sheet but are used as inner layers. Self-recycling material) can also be mixed, and a sheet material excellent in recyclability can be provided.

According to this invention, with respect to the above-mentioned multilayer sheet, a second hiding layer and the second hiding auxiliary layer, by laminating between the light-shielding layer and the non-colored layer, concealing of the sheet is more In particular, the concealability when viewed from the non-colored layer side is effective.
In addition, since the second hiding auxiliary layer is laminated side by side with the light shielding layer, and the light shielding layer is sandwiched between the hiding auxiliary layer and the second hiding auxiliary layer, the sheet is gradually increased from both sides to the inside. The blackness is increased, and the light shielding property of the entire sheet is further improved.

In the multilayer sheet of the present invention, it is preferable that the white pigment is titanium oxide and the black pigment is carbon black.
Titanium oxide has a fine particle size and is excellent in whiteness, concealability, colorability, and printability. By using titanium oxide as a white pigment in the multilayer sheet of the present invention, the whiteness, concealability, and color of the sheet And printability are improved. Moreover, since titanium oxide has good chemical resistance, light resistance, weather resistance, and heat resistance, these characteristics can be imparted by using titanium oxide as a white pigment in the multilayer sheet of the present invention. .
In addition, carbon black is excellent in light-shielding properties, light resistance, concealing properties, and coloring effects, and can be obtained at a low price. Therefore, by using carbon black as a black pigment in the multilayer sheet of the present invention, the light-shielding properties and light resistance of the sheet are obtained. Concealment is improved. In addition, coloring is easily performed in production, and a multilayer sheet can be provided at low cost.

In the multilayer sheet of the present invention, it is preferable that at least one of the above-described concealment auxiliary layer, second concealment auxiliary layer, and light shielding layer contains a recycled material (recycled material) of the multilayer sheet itself.
According to the present invention, since the recycled material of the multilayer sheet can be applied to the concealment auxiliary layer, the second concealment auxiliary layer, and the light shielding layer constituting the multilayer sheet, so-called self-recycling is possible and the recyclability is improved. An excellent multilayer sheet can be provided.
Further, by applying the recycled material to an inner layer that does not appear on the outer surface of the multilayer sheet, such as a concealment auxiliary layer or a light shielding layer, the appearance of the multilayer sheet is not affected.

The package of the present invention is a package made of the above-described multilayer sheet, wherein the non-colored layer is a layer in contact with the contents.
Since the package of the present invention is composed of the multilayer sheet of the present invention described above, it becomes a package that preferably exhibits the functions and effects exhibited by the multilayer sheet described above.
Further, since the non-colored layer constituting the multilayer sheet is a layer in contact with the contents, a pigment or the like does not adhere to the contents, and a sanitary good package can be provided.

[First Embodiment]
Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a cross-sectional view showing an embodiment of a multilayer sheet which is a multilayer laminate of the present invention. In FIG. 1, 1 is a multilayer sheet, 2 is a masking layer, 3 is a masking auxiliary layer, 4 is a light shielding layer, and 5 is a non-colored layer.

As shown in FIG. 1, the multilayer sheet 1 of the present embodiment is configured by laminating a hiding layer 2, a hiding auxiliary layer 3, a light shielding layer 4, and a non-colored layer 5 in this order.
Each layer constituting the multilayer sheet 1 has a predetermined base resin material as a basic constituent material. As the base resin material, it is preferable to use a thermoplastic resin that can be extruded. For example, polypropylene resin such as homopolypropylene (HPP), block polypropylene (BPP), random polypropylene (RPP), low density polyethylene ( LDPE), high density polyethylene (HDPE), polyethylene resins such as linear low density polyethylene (L-LDPE), and thermoplastic resins such as polystyrene resins such as general-purpose polystyrene (GPPS) and impact-resistant polystyrene (HIPS). It is done. These resins can be used alone or in combination, and elastomers can also be used in combination as necessary.

  In addition, various additives such as a heat stabilizer, a deodorant, an antibacterial agent, an antiblocking agent, and a slip agent can be appropriately blended with these thermoplastic resins as long as the effects of the present invention are not hindered. it can.

(I) Concealment layer 2:
The hiding layer 2 constituting the multi-layer sheet appears in the outermost layer of the multi-layer sheet 1 and plays a role of hiding the light-shielding layer 4, contains a white pigment, and adopts white as a hiding color. A clean feeling and hygiene can be imparted. Moreover, since the whole layer is white, coloring property and printability are also good.
The “white” in the present invention includes milky white.

  Examples of the white pigment used for concealing the entire layer in the concealing layer 2 include titanium oxide, zinc oxide (zinc white), zinc sulfide, barium sulfate, and lead white. It is preferable to use titanium oxide having a fine particle size, excellent whiteness, concealability, colorability, and printability, and having good chemical resistance, light resistance, weather resistance, and heat resistance.

The added amount of these white pigments is 1.5 g, with the total amount being 0.5 g / m ² or more with respect to the entire hiding layer 2 and hiding auxiliary layer 3 together with the white pigment used in hiding auxiliary layer 3 described later. / M ² or more is preferable. By adding the total amount of white pigment to the hiding layer 2 and the hiding auxiliary layer 3 so that the total amount of the white pigment is 0.5 g / m ² or more, the multilayer sheet 1 becomes a sheet having an excellent hiding effect by white color, and colorability Various performances such as printability are also improved. On the other hand, if the total amount of the white pigment added is less than 0.5 g / m ² , the concealing effect due to white color is deteriorated, and the above-described various performances may not be suitably exhibited.

(II) Concealment auxiliary layer 3:
The masking auxiliary layer 3 is laminated between the masking layer 2 described above and a light shielding layer 4 described later. The concealment auxiliary layer 3 is a white or gray layer.
Since the hiding auxiliary layer 3 is a white to gray layer as described above, a white pigment and, if necessary, a black pigment are added to the base resin material. As a usable white pigment, a white pigment similar to the white pigment used in the concealing layer 2 can be used. For the same reason, it is preferable to use titanium oxide.

  In order to provide the whole layer with light shielding properties in addition to the white hiding property, the hiding auxiliary layer 3 may be formed into a gray layer by using a black pigment together with the above-described white pigment. Examples of the black pigment used include carbon black, iron black, and graphite. Among these, it is preferable to use carbon black that is excellent in light shielding property, concealing property, and coloring effect and is available at low cost.

  In the multilayer sheet 1 of the present invention, as a constituent material of the concealment auxiliary layer 3, a recycled material (recycled material) of the multilayer sheet 1 itself may be mixed. Therefore, the multilayer sheet 1 is excellent in recyclability. Further, by applying the recycled material to the concealment auxiliary layer 3 that does not appear on the outer surface of the multilayer sheet 1, the appearance of the multilayer sheet 1 is not affected.

  In the relationship between the masking layer 2 and the masking auxiliary layer 3, the white pigment contained in the masking layer 2 needs to be higher in content than the white pigment contained in the masking auxiliary layer 3. Thereby, in the multilayer sheet 1, the brightness of the hiding layer 2 is larger than that of the hiding auxiliary layer 3, and the hiding layer 2 as the outermost layer becomes the highest in terms of whiteness (whiteness). The multilayer sheet 1 has a good appearance. Furthermore, by providing not only the masking layer 2 but also the masking auxiliary layer 3 having a lower whiteness than the masking layer 2, the multilayer sheet 1 having excellent masking properties can be obtained.

(III) Light shielding layer 4:
The light shielding layer 4 constituting the multilayer sheet 1 is laminated between the concealment auxiliary layer 3 and a non-colored layer 5 described later, and plays a role of imparting light shielding properties to the multilayer sheet 1.
Further, in the multilayer sheet 1 of the present invention, since the hiding auxiliary layer 3 having relatively high brightness is laminated side by side, the blackness gradually increases as viewed from the hiding layer 2, and the light shielding property of the entire sheet is increased. Will be improved.

The relationship between the light shielding layer 4 and the masking auxiliary layer 3 is that the white pigment content of the light shielding layer 4 is smaller than the white pigment content of the masking auxiliary layer 3 and the black pigment content of the light shielding layer 4 is the masking auxiliary. It must be greater than the content of black pigment in layer 3. Thereby, in the multilayer sheet 1, the brightness of the hiding auxiliary layer 3 is larger than that of the light shielding layer 4, and the brightness of the light shielding layer 4 is the smallest in the multilayer sheet 1, so that the black color is gradually increased toward the inside of the sheet. The degree (blackness) becomes high, and the multilayer sheet 1 has a high light shielding property against external light. Then, the concealment auxiliary layer 3 laminated between the concealment layer 2 and the light shielding layer 4 can improve the concealment property of the sheet and improve the light shielding property of the sheet.
In the present invention, the relationship between the white pigment content in the masking layer 2 and the masking auxiliary layer 3 and the relationship between the white pigment and the black pigment in the masking auxiliary layer 3 and the light shielding layer 4 are both What is necessary is just to make it the standard of the content rate (mass%) of the white pigment and the black pigment with respect to each layer. Similarly, the relationship between the content of white pigment in the second hiding layer and the second hiding auxiliary layer described later, the relationship between the white pigment and the black pigment in the second hiding auxiliary layer and the light shielding layer 4, What is necessary is just to make it the standard of the content rate (mass%) of the white pigment and the black pigment with respect to each layer.

  In the light shielding layer 4, examples of the black pigment used for giving light shielding properties to the entire layer include the same black pigments as those mentioned in the concealment auxiliary layer 3, and the same reason as described above. Therefore, it is preferable to use carbon black.

  The addition amount of the black pigment is 0.03 to 1.0% by mass, and 0.05 to 0.5% by mass with respect to the entire multilayer sheet 1 by combining the light shielding layer 4 and the above-described concealment auxiliary layer 3. It is preferable. If the amount of the black pigment added is within such a range, good light shielding properties can be imparted to the multilayer sheet 1. On the other hand, if the addition amount of the black pigment is less than 0.03% by mass, good light shielding properties may not be obtained. If the addition amount of the black pigment is more than 1.0% by mass, the resulting light shielding effect is different. This is not economical and may adversely affect the formability of the multilayer sheet 1.

  The light shielding layer 4 is basically a black layer, but a white pigment may be added depending on the required light shielding performance. As the white pigment, a white pigment similar to the white pigment used in the hiding layer 2 and the hiding auxiliary layer 3 can be used, and titanium oxide is preferably used for the same reason.

  In addition, it is preferable to set the thickness of this light shielding layer 4 in the range of 2-40% with respect to the multilayer sheet 1 whole, and it is especially preferable to set it as 4-10%. Thus, the light shielding property of the whole multilayer sheet 1 can be made favorable by setting the thickness ratio of the light shielding layer 4 within the range of 2 to 40% with respect to the whole multilayer sheet 1.

  In the multilayer sheet 1 of the present invention, as in the case of the concealment auxiliary layer 3, the recycled material (recycled material) of the multilayer sheet 1 itself may be mixed as the constituent material of the light shielding layer 4. By doing so, it is possible to provide the multilayer sheet 1 having excellent recyclability and capable of so-called self-recycling. Further, by applying the recycled material to the light shielding layer 4 that does not appear on the outer surface of the multilayer sheet 1, similarly to the concealment auxiliary layer 3, the appearance of the multilayer sheet 1 is not affected.

(IV) Non-colored layer 5:
The non-colored layer 5 is a layer that is in contact with the food or the like that is the product to be packaged in the sheet material, and can impart a clean feeling to the multilayer sheet by not containing the colored pigment.
Here, as the constituent material of the non-colored layer 5, the above-described base resin material may be used as it is.

  In order to obtain the multilayer sheet 1 having the above-described configuration, it may be produced in advance as a sheet-like form by a general-purpose means such as an inflation method or a T-die method, and then laminated by a known laminating means. The layers constituting the multilayer sheet 1 may be extruded by coextrusion laminating using the above extruder, and each layer may be formed at once.

Although there is no restriction | limiting in particular as the thickness of the multilayer sheet 1 whole, 150-1500 micrometers is preferable.

The multilayer sheet 1 preferably has a total light transmittance of 5% or less, particularly preferably 1% or less. By setting the total light transmittance to 5% or less, it is possible to provide the multilayer sheet 1 having excellent light shielding properties.
In addition, what is necessary is just to measure the total light transmittance of the multilayer sheet 1 based on JISK7105.

  The multilayer sheet 1 is preferably applied as a package for packaging various articles such as food, and the form of the formed package includes a vertical pillow bag, a horizontal pillow bag made of the above-described sheet (film), Various forms of packaging such as four-side sealed bags, three-side sealed bags, gusset bags, self-supporting bags, molded containers, and container lids can be employed.

  Further, when the multilayer sheet 1 is applied as a package, if the non-colored layer 5 constituting the multilayer sheet is a layer in contact with the contents such as food, pigments and the like adhere to the contents. Without sanitary, it becomes a package that is hygienic.

  Such a multilayer sheet 1 of the present invention is excellent in light-shielding and concealing properties, and also has good hygiene, so that, for example, beverages, fruit juices, juices, drinking water, liquor, cooked foods, marine products, frozen foods, frozen foods, etc. It can be widely used as a packaging material for packaging foods, boiled foods, rice cakes, liquid soups, seasonings, other various foods and drinks, liquid detergents, chemical products, cosmetics, and other various articles.

According to the multilayer sheet 1 of the first embodiment obtained as described above, the following effects can be obtained.
(1) The hiding layer 2 and the hiding auxiliary layer 3 contain 0.5 g / m ² or more of the total amount of white pigment,
Since the white pigment of the hiding layer 2 has a higher content than the white pigment of the hiding auxiliary layer 3,
In the multilayer sheet 1, the lightness of the hiding layer 2 is larger than that of the hiding auxiliary layer 3 (whiteness becomes higher), and the sheet has a good appearance with a clean feeling. Further, by further providing a hiding auxiliary layer 3 having a lower whiteness (smaller brightness) than the hiding layer 2, a sheet having excellent hiding properties can be obtained.

(2) The black pigment contained in the light shielding layer 4 and the hiding auxiliary layer 3 is 0.03 to 1% by mass with respect to the entire multilayer sheet 1, and the white pigment of the light shielding layer 4 is more than the white pigment of the hiding auxiliary layer 3. Since the content ratio is small and the black pigment of the light shielding layer 4 is larger in content than the black pigment of the masking auxiliary layer 3, the blackness gradually increases toward the inner side of the multilayer sheet 1, and the light shielding against external light is performed. It becomes a sheet with high properties.

(3) Further, since the concealment auxiliary layer 3 exhibiting white or gray and the light shielding layer 4 exhibiting gray or black are not shown on the outer surface of the sheet as an intermediate layer, the sheet structure is self-contained. It is possible to mix recycled materials. Furthermore, since the recycled material of the multilayer sheet 1 itself can be applied to the concealment auxiliary layer 3 and the light shielding layer 4, the multilayer sheet 1 excellent in recyclability can be provided. Then, by applying the recycled material to an intermediate layer that does not appear on the outer surface of the multilayer sheet 1, such as the hiding auxiliary layer 3 or the light shielding layer 4, the appearance and the like of the multilayer sheet 1 can be maintained in a good state. .

(4) By using titanium oxide as the white pigment in the multilayer sheet 1, the whiteness, concealability, colorability, and printability of the sheet are improved. Further, since titanium oxide has good chemical resistance, light resistance, weather resistance, and heat resistance, these characteristics can be imparted by using titanium oxide as a white pigment in the multilayer sheet 1 of the present invention. it can.
Further, since carbon black is excellent in light-shielding property, light resistance, concealing property and coloring effect and can be obtained at a low price, the use of carbon black as the black pigment in the multilayer sheet 1 of the present invention enables the light-shielding property and light resistance of the sheet. And concealment are improved. In addition, coloring is easily performed in production, and the multilayer sheet 1 can be provided at low cost.

(5) If the multilayer sheet 1 is used as a constituent material of the package, a package that suitably exhibits the functions and effects of the above (1) to (4) can be provided.
In addition, if the non-colored layer 5 constituting the multilayer sheet 1 is a layer in contact with the contents, a pigment or the like does not adhere to the contents, and a package that is hygienic can be provided.

[Second Embodiment]
Next, another embodiment of the present invention will be described with reference to the drawings.
FIG. 2 is a cross-sectional view showing another aspect of the multilayer sheet 1a of the present invention. The multilayer sheet 1a of the present embodiment includes a masking layer 2, a masking auxiliary layer 3, a light shielding layer 4, and a second masking auxiliary layer. 3a, the 2nd concealing layer 2a, and the non-colored layer 5 are laminated | stacked in this order.
In the following description, members and the like that are the same as those already described in the first embodiment are denoted by the same reference numerals, and description thereof is omitted.

The multilayer sheet 1a of the present embodiment is different from the configuration of the multilayer sheet 1 of the first embodiment described above between the light shielding layer 4 and the non-colored layer 5 between the second hiding auxiliary layer 3a and the second hiding auxiliary layer 3a. The hiding layer 2a is provided in this order.
Here, the specifications of each layer such as the material and thickness of the hiding layer 2, the hiding auxiliary layer 3, the light shielding layer 4, and the non-colored layer 5 constituting the multilayer sheet 1a are the hiding layers constituting the first embodiment described above. 2, can be made to conform to the contents described for the hiding auxiliary layer 3, the light shielding layer 4, the non-colored layer 5,
The second hiding layer 2a may be configured in accordance with the hiding layer 2, and the second hiding auxiliary layer 3a may be configured in accordance with the hiding auxiliary layer 3.

That is, in the multilayer sheet 1a in the second embodiment, the total amount of white pigments contained in the hiding layer 2 and the hiding auxiliary layer 3 is 0.5 g / m ² or more as a relationship between the hiding layer 2 and the hiding auxiliary layer 3. The content of the white pigment in the masking layer 2 is larger than the content of the white pigment in the masking auxiliary layer 3, and the relationship between the masking auxiliary layer 3 and the masking layer 4 is contained in the masking layer 4 and the masking auxiliary layer 3. The black pigment is 0.03 to 1% by mass with respect to the multilayer sheet 1, the white pigment content of the light shielding layer 4 is smaller than the white pigment content of the masking auxiliary layer 3, and the black pigment of the light shielding layer 4 The content is the same as that of the multilayer sheet 1 of the first embodiment in that the content is larger than the content of the black pigment in the masking auxiliary layer 3.

In addition, the relationship between the second concealment layer 2a and the second concealment auxiliary layer 3a may be the same as the relationship between the concealment layer 2 and the concealment auxiliary layer 3 described above. The total amount of white pigments contained in the masking auxiliary layer 3a is 0.5 g / m ² or more, and the white pigment content of the second masking auxiliary layer 2a is greater than the white pigment content of the second masking auxiliary layer 3a. The black pigment contained in the light shielding layer 4, the masking auxiliary layer 3 and the second masking auxiliary layer 3a is also added to the multilayer sheet because of the large size and the relationship between the second masking auxiliary layer 3a and the light shielding layer 4. The content of white pigment in the light shielding layer 4 is smaller than the content of white pigment in the second masking auxiliary layer 3a, and the content of black pigment in the light shielding layer 4 is second. What is necessary is just to make it larger than the content rate of the black pigment of the concealment auxiliary layer 3a.

Here, by laminating the second hiding layer 2a and the second hiding auxiliary layer 3a between the light shielding layer 4 and the non-colored layer 5, the hiding property of the sheet is further improved. This is effective for concealment when viewed from the layer 5 side.
Further, since the second hiding auxiliary layer 3a is laminated side by side with the light shielding layer 4, and the light shielding layer 4 is sandwiched between the hiding auxiliary layer 3 and the second hiding auxiliary layer 3a, the sheet is directed inward from both sides of the sheet. As a result, the blackness is gradually increased, and the light shielding property of the entire multilayer sheet 1a is further improved.

Moreover, in order to produce the multilayer sheet 1a of the present embodiment, after being produced in advance as a sheet-like form by general-purpose means such as an inflation method and a T-die method, as with the multilayer sheet 1 of the first embodiment, You may laminate | stack by a well-known lamination means.
In addition, by using a plurality of extruders, the layers constituting the multilayer sheet 1 may be extruded by coextrusion laminating, and each layer may be formed at once. It is preferable to form a film by combining a machine and a feed block, whereby a film having a uniform thickness distribution can be formed. In the coextrusion lamination, the film can be formed by, for example, four extruders as in the first embodiment.

According to the multilayer sheet 1a of the second embodiment, in addition to the effects (1) to (5) exhibited by the multilayer sheet 1 described in the first embodiment, the following effects can be achieved.
(6) As a configuration of the multilayer sheet 1a, the second hiding layer 2a and the second hiding auxiliary layer 3a are laminated between the light shielding layer 4 and the non-colored layer 5 to further improve the hiding property of the sheet. In addition, since both sides of the sheet are white, the cleanliness of the sheet is further improved.
Then, the second concealment auxiliary layer 3a is laminated side by side with the light shielding layer 4, and the light shielding layer 4 is sandwiched between the concealment auxiliary layer 3 and the second concealment auxiliary layer 3a. It will be excellent.

  The aspect described above shows one aspect of the present invention, and the present invention is not limited to the above-described embodiment, and is within the scope of achieving the object and effect of the present invention. Needless to say, modifications and improvements are included in the content of the present invention. Further, the specific structure, shape, and the like in carrying out the present invention are not problematic as other structures, shapes, and the like as long as the objects and effects of the present invention are achieved.

  For example, in the above-described embodiment, a specific thermoplastic resin material has been described as the base resin material. For example, the light shielding layer 4 has an excellent oxygen gas barrier property in order to improve the oxygen gas barrier property. Alternatively, a resin material (oxygen gas barrier material) may be used. Examples of the oxygen gas barrier material include resins such as ethylene-vinyl alcohol copolymer (EVOH), polyvinylidene chloride (PVDC), and nylon (polyamide). By constituting each layer such as the light shielding layer 4 with these oxygen gas barrier materials, the oxygen gas barrier property can be imparted to the multilayer sheets 1 and 1a by a simple means.

In addition, when these oxygen gas barrier materials are applied to the light shielding layer 4, an adhesive layer made of a polyolefin-based adhesive polymer or the like is formed on both surfaces of the layer at the time of coextrusion molding. You may do it.
In addition, the specific structure, shape, and the like in the implementation of the present invention may be other structures as long as the object of the present invention can be achieved.

  EXAMPLES Hereinafter, although an Example and a comparative example are given and this invention is demonstrated more concretely, this invention is not limited to the content of this Example etc.

[Manufacture of multilayer sheets]
The multilayer sheets 1a of Examples 1 to 13 and Comparative Examples 1 to 4 having the layer configuration of FIG. 2 (second embodiment) described above and using the following manufacturing conditions were manufactured. The specifications of each layer of the multilayer sheet 1a are shown in Tables 1 and 2.

(Production conditions)
In FIG. 2, an extruder A for extruding the light shielding layer 4, a hiding auxiliary layer 3, an extruder B for extruding the second hiding auxiliary layer 3a, a hiding layer 2, an extruder C for extruding the second hiding layer, and a non-colored layer Extruder 5 that extrudes 5 is used, and for this extruder, a multi-layer coextrusion production apparatus equipped with a feed block of 4 types and 6 layers is used. According to the raw materials used, a 6-layer multilayer sheet 1a (thickness: 300 μm, but Example 11 had a thickness of 1500 μm) was produced by a coextrusion method.
In addition, as a base material resin material common to each layer, impact-resistant polystyrene (manufactured by ET-64 PS Japan) was used.

(Thickness of multilayer sheet: sheet thickness 300 μm)
Layer thickness (ratio to the whole sheet)
Concealment layer 2 30 μm (10%)
Concealment auxiliary layer 3 90μm (30%)
Light-shielding layer 4 30 μm (10%)
Second concealment auxiliary layer 3a 90 μm (30%)
Second hiding layer 2a 30 μm (10%)
Non-colored layer 5 30 μm (10%)

(Extruder A: For light shielding layer 4)
An extruder with a screw diameter of 50 mmφ was used. As a raw material used, carbon black (ESH-K-4799LB: manufactured by Polycol Kogyo Co., Ltd.) was added to the impact-resistant polystyrene of the base resin material so as to be substantially 2.5% by mass (carbon black). A masterbatch containing 40% by weight was used).

(Extruder B: Concealment auxiliary layer 3, second concealment auxiliary layer 3a)
An extruder with a screw diameter of 90 mmφ was used. As a raw material used, 20% of the recycled material of the multilayer sheet of the present invention having the following specifications was added to the impact-resistant polystyrene of the base resin material.

  In addition, the multilayer sheet used for the recycled material used in Examples 1 to 13 and Comparative Example 1 is a multilayer sheet recycled material having the same configuration as that described in Tables 1 and 2 for the Examples and the like. In addition, it was made to contain with respect to each layer at the ratio described in each example and comparative example.

(Extruder C: Concealment layer 2 and second concealment layer 2a)
An extruder with a screw diameter of 65 mmφ was used. As a raw material to be used, a material obtained by adding titanium oxide (ECE9338: manufactured by Polycol Kogyo Co., Ltd.) to 5.0 mass% with respect to the impact-resistant polystyrene of the base resin material was used. (A master batch containing 47% by mass of titanium oxide was used.)

(Extruder D: For non-colored layer 5)
An extruder with a screw diameter of 65 mmφ was used. As the raw material used, the impact-resistant polystyrene of the base resin material was used as it was.

[Example 1]
Using the raw materials used in the above-described extruders A to D, the multilayer sheet 1a of the present invention having the structure shown in Table 1 for each layer was produced.

[Example 2]
In Example 1, each layer was shown in Table 1 using the same method as in Example 1 except that the addition amount of carbon black in Extruder A was changed from 2.5% by mass to 5.0% by mass. The multilayer sheet 1a of the present invention having the structure was manufactured.

[Example 3]
The configuration shown in Table 1 for each layer was the same as in Example 1 except that the amount of carbon black added in Extruder A was changed from 2.5% by mass to 0.3% by mass in Example 1. The multilayer sheet 1a of the present invention was produced.

[Example 4]
In Example 3, except that the amount of carbon black added in Extruder B was changed from 0% by mass to 0.05% by mass, each layer had the structure shown in Table 1 using the same method as Example 3. A multilayer sheet 1a of the present invention was produced.

[Example 5]
In Example 1, each layer showed in Table 1 using the same method as Example 1 except having changed the addition amount of the titanium oxide in the extruder C from 5.0 mass% to 3.0 mass%. The multilayer sheet 1a of the present invention having the structure was manufactured.

[Example 6]
In Example 1, except that the amount of carbon black added in Extruder A was changed from 2.5% by mass to 8% by mass, each layer had the structure shown in Table 1 using the same method as Example 1. A multilayer sheet 1a of the present invention was produced.

[Example 7]
In Example 1, except that the content rate of the recycled material in the extruder B was changed from 20% by mass to 100% by mass, the same method as in Example 1 was used, and each layer of the present invention having the configuration shown in Table 1 was used. A multilayer sheet 1a was produced.

[Example 8]
In Example 1, 1% by mass of carbon black was added to the raw material used in the extruder A, and the remainder was all recycled material. Also, 4% by mass of titanium oxide is added as a base resin material without adding a recycled material to the extruder B, and the addition amount of titanium oxide in the extruder C is further increased from 5.0% to 7. Using the same method as in Example 1 except that the amount was changed to 0% by mass, a multilayer sheet 1a of the present invention having the configuration shown in Table 1 for each layer was produced.

[Example 9]
In Example 1, the ratio of the thickness of the light shielding layer 4 to the entire multilayer sheet 1a is 10% to 40%, the amount of carbon black added in the extruder A is 2.5% to 1.0% by mass, and the multilayer sheet 1a Each layer has the structure shown in Table 1 using the same method as in Example 1 except that the ratio of the thickness of the entire hiding auxiliary layer 3 and the second hiding auxiliary layer 3a is 30% to 15%. A multilayer sheet 1a of the present invention was produced.

[Example 10]
In Example 1, the ratio of the thickness of the light shielding layer 4 to the entire multilayer sheet 1a is 10% to 4%, the amount of carbon black added in the extruder A is 2.5 mass% to 8.0 mass%, and the multilayer sheet The structure shown in Table 1 using the same method as in Example 1 except that the ratio of the thickness of the concealment auxiliary layer 3 and the second concealment auxiliary layer 3a in the entire la is 30% to 33%. The multilayer sheet 1a of the present invention was produced.

[Example 11]
Using the same method as in Example 1 except that the thickness of the sheet was changed from 300 μm to 1500 μm, a multilayer sheet 1 a according to the present invention having the structure shown in Table 1 was manufactured. In addition, the thickness of each layer in Example 11 is as follows.

(Thickness of multilayer sheet: sheet thickness 1500 μm)
Layer thickness (ratio to the whole sheet)
Concealment layer 2 150 μm (10%)
Concealment auxiliary layer 3 450μm (30%)
Light-shielding layer 4 150 μm (10%)
Second concealment auxiliary layer 3a 450 μm (30%)
Second hiding layer 2a 150 μm (10%)
Non-colored layer 5 150 μm (10%)

[Example 12]
Add 50mmφ Extruder A, replace the equipment with 5 types and 8 layers of feed block, and use Extruder A to push out the light shielding layer 4 Adhesive (Mersen MX13: manufactured by Tosoh Corporation) / Extruder A ' To ethylene-vinyl alcohol copolymer (Eval J102B: manufactured by Kuraray Co., Ltd.) / Extruder A to adhesive (Mersen MX13: manufactured by Tosoh Co., Ltd.) so that the thickness becomes 10 μm / 10 μm / 10 μm. A multilayer sheet 1a of the present invention having the structure shown in Table 1 was produced using the same method as in Example 1 except that the sheet was extruded.

[Example 13]
In Example 1, except that the base resin material was changed from impact-resistant polystyrene to homopolypropylene (Idemitsu Polypro E105: manufactured by Idemitsu Petrochemical Co., Ltd.), each layer was represented using the same method as in Example 1. A multilayer sheet 1a according to the present invention having the structure shown in FIG.

[Comparative Example 1]
In Example 1, each layer was shown in Table 1 using the same method as Example 1 except having changed the addition amount of the titanium oxide in the extruder A from 2.5 mass% to 1.0 mass%. A multi-layer sheet of construction was produced.

[Comparative Example 2]
In Example 1, the raw materials used in the extruders A to D were the same as in Example 1 except that 1.0% by mass of titanium oxide was added to the impact-resistant polystyrene as the base resin material. Using such a method, a multilayer sheet having the structure shown in Table 1 for each layer was produced.

[Comparative Example 3]
A multilayer sheet having the structure shown in Table 1 using the same method as in Comparative Example 2 except that the amount of titanium oxide added was changed from 1.0% by mass to 4.0% by mass in Comparative Example 2. Manufactured.

[Comparative Example 4]
In Comparative Example 2, a multilayer sheet having the structure shown in Table 1 using the same method as in Comparative Example 2, except that the same amount (1.0% by mass) of carbon black was added instead of titanium oxide. Manufactured.

  In addition, Table 1 shows the configurations of the multilayer sheets obtained in Examples 1 to 13 and Comparative Examples 1 to 4, Table 2 shows the content of titanium oxide that is a white pigment in the multilayer sheet, and Table 3 shows multilayers. The content of carbon black, which is a black pigment in the sheet, is shown.

(Configuration of multilayer sheet)

(Content of titanium oxide in multilayer sheet)

(Carbon black content in multilayer sheet)

[Test Example 1]
The multilayer sheets of Examples 1 to 13 and Comparative Examples 1 to 4 obtained as described above were compared and evaluated by confirming (1) light shielding properties and (2) concealing properties under the following conditions. The results are shown in Table 4.

(1) Light shielding properties:
The light blocking property was measured using a commercially available measuring instrument (manufactured by Nippon Denshoku Industries Co., Ltd.) in accordance with JIS K7105 for the total light transmittance (%) of the multilayer sheet.

(2) Concealment:
The multilayer sheet was visually confirmed and judged according to the following criteria.

(Criteria)
Judgment details
○ Good concealment
△ Slightly good concealment
× Poor concealment

(Result)

As can be seen from the results in Table 4, it was confirmed that the multilayer sheets of the present invention obtained in Examples 1 to 13 were sheet materials excellent in light shielding properties and hiding properties.
The multilayer sheets of Examples 1 to 13 had no effect on the evaluated sheet characteristics when the self-recycled material was applied to the hiding auxiliary layer, the second hiding auxiliary layer, and the light shielding layer. Thereby, it has confirmed that the multilayer sheet of this invention was a sheet material excellent also in recyclability.

On the other hand, the multilayer sheet of Comparative Example 1 having a small titanium oxide content in the masking layer and the second masking layer, and the masking auxiliary layer and the second masking auxiliary layer had poor masking properties.
In addition, the multilayer sheets of Comparative Examples 2 and 3 in which titanium oxide was added to each layer had poor total light transmittance and poor light shielding properties.
And the multilayer sheet | seat of the comparative example 4 which added carbon black with respect to each layer had bad concealment property.

  The multilayer sheet of the present invention and the package comprising the multilayer sheet are, for example, beverages, fruit juices, juices, drinking water, liquor, cooked foods, aquatic foods, frozen foods, boiled foods, rice cakes, liquid soups, seasonings, etc. It can be widely used as a packaging material for packaging various foods and drinks, liquid detergents, chemical products, cosmetics, and other various articles.

It is sectional drawing which shows one Embodiment of the multilayer sheet of this invention. It is sectional drawing which shows other embodiment of the multilayer sheet of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1,1a ... Multilayer sheet 2 ... Concealment layer 2a ... Second concealment layer 3 ... Concealment auxiliary layer 3a ... Second concealment auxiliary layer 4 ... Light shielding layer 5 ... Non-colored layer

Claims (5)

And concealing layer containing a white pigment, and concealing the auxiliary layer containing a white pigment及beauty black color pigment, and the light-shielding layer containing Kokushokukao fee, a non-colored layer or a multilayer sheet comprising in this order,
Between the light-shielding layer and the non-colored layer comprises a second concealment auxiliary layer containing a white pigment及beauty black color pigment, the second shielding layer containing a white pigment in this order,
The white pigment hiding layer has a larger content than the white pigment of the hiding auxiliary layer,
The second white pigment hiding layer has a larger content than the white pigment of the second concealment auxiliary layer,
The white pigment light-shielding layer is smaller content than the white pigment of the hiding auxiliary layer and the second hiding auxiliary layer,
The hiding layer and the second hiding layer each have a white pigment content of 0.97 to 8.21 g / m ² ,
The concealing auxiliary layer and the second concealing auxiliary layer each have a white pigment content of 0.10 to 3.91 g / m ² ,
The light shielding layer, the hidden auxiliary layer and the black pigment contained in the second concealment auxiliary layer is a 0.03 to 1 wt% relative to the multilayer sheet,
The multilayer sheet , wherein the black pigment of the light shielding layer has a larger content than the black pigment of the concealment auxiliary layer and the second concealment auxiliary layer.   The multilayer sheet according to claim 1,
  The light shielding layer has a black pigment content of 0.30 to 8.00 mass%,
  Each of the hiding auxiliary layer and the second hiding auxiliary layer has a black pigment content of 0.01 to 0.25% by mass.
  A multilayer sheet characterized by that. In the multilayer sheet according to claim 1 or 2,
The white pigment is titanium oxide;
A multilayer sheet, wherein the black pigment is carbon black. In the multilayer sheet according to any one of claims 1 to 3,
Multilayer sheet wherein the concealing auxiliary layer, said second concealing the auxiliary layer and the light-shielding layer at least one layer, characterized in that it contains recycled material of the multilayer sheet itself (recycled material). A package comprising the multilayer sheet according to any one of claims 1 to 4,
The packaging body, wherein the non-colored layer is a layer in contact with the contents.

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